Bio-oil formulation as an asphalt substitute

ABSTRACT

A bio-oil formulation, useful as an asphalt binder substitute in pavement and roofing shingles, includes bio-oil and a polymer additive. The bio-oil binder can include an asphalt additive. The bio-oil binder can be emulsified with water and a surfactant for use as a weatherproofing sealant or as an adhesive. A method for making the bio-oil binder is disclosed.

This application is a divisional application of U.S. patent applicationSer. No. 13/149,183, filed May 31, 2011, and claims the benefit of U.S.Provisional Patent Application Ser. No. 61/350,199, filed Jun. 1, 2010,which are hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to the use of a bio-oil formulation as an asphaltsubstitute. In particular, the invention relates to the use of bio-oilformulations as replacement for asphalt binders in various applications,and methods for the production thereof.

BACKGROUND OF THE INVENTION

Asphalt or flexible pavement is typically built with several layers toform a layered system with better materials at the top where the stressintensity is high and inferior materials at the bottom where the stressintensity is low. The top layer, called the surface course, is typicallymade of an asphalt mixture. All types of failure or distress can beclassified by whether they are structural or functional failures andload associated or non-load associated distresses.

Most bituminous adhesives or binders that are used for pavementmaterials are derived primarily from fossil fuels. Nevertheless, withpetroleum oil reserves becoming depleted and the subsequent urge toreduce fossil fuel usage, there is a drive to develop and producebinders from alternative sources, particularly from biorenewableresources. Over the years, biorenewable natural resources includingsugars, triglyceride oils and proteins have been tested as alternativesources for producing adhesives and binders. For example, adhesivesderived from soy protein, starch, cellulose and other polysaccharideshave been extensively used for adherents such as wood, paper, plastic,metal, leather and glass. Due to the availability of large quantities ofbiorenewable sources such as triglyceride oils, proteins, starch andother carbohydrates from different botanical sources, there are virtuoustechnical and economic prospects in utilizing them to producebio-binders.

Recently, through the application of scientific research anddevelopment, a range of different vegetable oils have been investigatedto determine their physical and chemical properties to study theirapplicability to be used as bio-binders in the pavement industry.Applicants have found this development to be useful in overcoming thedeficiencies in the art.

SUMMARY OF THE INVENTION

One aspect of the present invention is directed to a composite materialthat includes a mineral aggregate and a bio-oil binder. The bio-oilbinder contains bio-oil and a polymer additive.

Another aspect of the present invention relates to an asphalt bindersubstitute containing a bio-oil binder which includes bio-oil and apolymer additive.

A further aspect of the present invention relates to a method for theproduction of an asphalt binder substitute. This method includespretreating a bio-oil by mechanical mixing at a temperature of fromabout 100° C. to about 130° C. As a result, the bio-oil achieves aviscosity of less than about 3 Pa·s at a temperature of from about 100°C. to about 130° C. and is equivalent to the bio-oil being mixed at atemperature of from about 100° C. to about 130° C. This gives thebio-oil an aging index of less than about 12 after from about 2 to about8 hours. A polymer additive is then added to the pretreated bio-oil, andthe blend is heated at a temperature of from about 100° C. to about 130°C. The heated blend is then treated to a viscosity between about 100 andabout 1000 cps when measured in a rotational viscometer at about 20 rpmand a temperature of from about 100° C. to about 130° C.

The benefits of this technology include a low cost asphalt bindersubstitute that performs as well as asphalt binders currently beingused. Further, the bio-oil binder likely lowers hot mix asphalt plantproduction temperatures, and thus reduces plant emissions. Lastly, thebio-oil binder represents the development of greenmaterials/technologies that are renewable, and lessen the reliance onforeign crude oil.

The conversion of residual biomass such as corn stover or forestproducts provides added economic opportunity for property owners overthat of the crops being harvested, and used in fast pyrolysis to producematerials that can be used in lieu of asphalt. The bio-oil can also beused in combination with ground recycled tire rubber to enhance the lowtemperature elastic properties of the combined binder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of aging index relative to zero hours for oakwoodblends before treatment at 125° C.

FIG. 2 is a plot of aging index relative to two hours for oakwood blendsbefore treatment at 125° C.

FIG. 3 is a plot of aging index relative to zero hours for oakwoodblends before treatment at 135° C.

FIG. 4 is a plot of aging index relative to two hours for oakwood blendsbefore treatment at 135° C.

FIG. 5 is a plot of viscosity over time for oakwood blends beforetreatment at 125° C.

FIG. 6 is a plot of viscosity over time for switchgrass blends beforetreatment at 125° C.

FIG. 7 is a plot of viscosity over time for cornstover blends beforetreatment at 125° C.

FIG. 8 is a plot of viscosity over time for oakwood blends beforetreatment at 135° C.

FIG. 9 is a plot of viscosity over time for switchgrass blends beforetreatment at 135° C.

FIG. 10 is a plot of viscosity over time for cornstover blends beforetreatment at 135° C.

FIG. 11 is a plot of aging index relative to zero hours for oakwoodblends before treatment at 125° C.

FIG. 12 is a plot of aging index relative to zero hours for switchgrassblends before treatment at 125° C.

FIG. 13 is a plot of aging index relative to zero hours for cornstoverblends before treatment at 125° C.

FIG. 14 is a plot of aging index relative to two hours for oakwoodblends before treatment at 125° C.

FIG. 15 is a plot of aging index relative to two hours for switchgrassblends before treatment at 125° C.

FIG. 16 is a plot of aging index relative to two hours for cornstoverblends before treatment at 125° C.

FIG. 17 is a plot of aging index relative to zero hours for oakwoodblends before treatment at 135° C.

FIG. 18 is a plot of aging index relative to zero hours for switchgrassblends before treatment at 135° C.

FIG. 19 is a plot of aging index relative to zero hours for cornstoverblends before treatment at 135° C.

FIG. 20 is a plot of aging index relative to two hours for oakwoodblends before treatment at 135° C.

FIG. 21 is a plot of aging index relative to two hours for switchgrassblends before treatment at 135° C.

FIG. 22 is a plot of aging index relative to two hours for cornstoverblends before treatment at 135° C.

FIG. 23 is a plot of viscosity over time for oakwood blends aftertreatment at 125° C.

FIG. 24 is a plot of viscosity over time for switchgrass blends aftertreatment at 125° C.

FIG. 25 is a plot of viscosity over time for cornstover blends aftertreatment at 125° C.

FIG. 26 is a plot of viscosity over time for oakwood blends aftertreatment at 135° C.

FIG. 27 is a plot of viscosity over time for switchgrass blends aftertreatment at 135° C.

FIG. 28 is a plot of viscosity over time for cornstover blends aftertreatment at 135° C.

FIG. 29 is a plot of aging index relative to zero hours for oakwoodblends after treatment at 125° C.

FIG. 30 is a plot of aging index relative to zero hours for switchgrassblends after treatment at 125° C.

FIG. 31 is a plot of aging index relative to zero hours for cornstoverblends after treatment at 125° C.

FIG. 32 is a plot of aging index relative to zero hours for oakwoodblends after treatment at 135° C.

FIG. 33 is a plot of aging index relative to zero hours for switchgrassblends after treatment at 135° C.

FIG. 34 is a plot of aging index relative to zero hours for cornstoverblends after treatment at 135° C.

FIG. 35 is a Richards Curve plot.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the present invention is directed to a composite materialthat includes a mineral aggregate and a bio-oil binder. The bio-oilbinder contains bio-oil and a polymer additive.

Another aspect of the present invention relates to an asphalt bindersubstitute containing a bio-oil binder which includes bio-oil and apolymer additive.

A further aspect of the present invention relates to a method for theproduction of an asphalt binder substitute. This method includespretreating a bio-oil by mechanical mixing at a temperature of fromabout 100° C. to about 130° C. As a result, the bio-oil achieves aviscosity of less than about 3 Pa·s at a temperature of from about 100°C. to about 130° C. and is equivalent to the bio-oil being mixed at atemperature of from about 100° C. to about 130° C. This gives thebio-oil an aging index of less than about 12 after from about 2 to about8 hours. A polymer additive is then added to the pretreated bio-oil, andthe blend is heated at a temperature of from about 100° C. to about 130°C. The heated blend is then treated to a viscosity between about 100 andabout 1000 cps when measured in a rotational viscometer at about 20 rpmand a temperature of from about 100° C. to about 130° C.

Bio-oil produced from fast pyrolysis process of biomass provides asource of lignin-derived oligomers. One route to convert lignocellulosicbiomass to produce chemicals and fuels that has gained serious attentionmore recently is a fast pyrolysis platform. Fast pyrolysis is the rapidthermal decomposition of organic compounds in the absence of oxygen toproduce liquids, gases, and chars. The distribution of products dependson the biomass composition, particle size, and rate and duration ofheating. Liquid yields as high as 78% are possible. The liquid productcan substitute for fuel oil in static heating or electricity generationapplication. In addition, the liquid can also be used to produce a rangeof specialty and commodity chemicals, such as levoglucosene,fertilizers, and hydrogen. Depending on its original lignocellulosicbiomass source, bio-oil contains between 10 to 30% lignin-derivedoligomers by weight.

In the fast pyrolysis process, biomass is heated rapidly in a hightemperature environment, yielding a mix of liquid fuel (bio-oil),combustible gases, and solid char. Pyrolysis is an independentconversion technology, as well as a part of the gasification process.Gasification can be separated into two main stages: 1) soliddevolatilization (pyrolysis) and 2) char conversion (combustion andgasification). Fast pyrolysis converts biomass into liquid form, whichhas higher bulk density and heating value, thus it is easier and moreeconomical to store and/or transport compared to the bulky biomass. Theliquid product resulting from biomass pyrolysis is commonly referred toas “pyrolysis oil,” “bio-fuel oil,” or simply “bio-oil.”

One embodiment of a suitable bio-oil composition which is suitable foruse in the present invention includes 0 to 2.1 wt % miscellaneousoxygenates, 0 to 0.85 wt % furans, 0.73 to 1.82 wt % phenols, 0.48 to0.7 wt % guaiacols (i.e. methoxy phenols), 0.55 to 1.48 wt % syringols(i.e. dimethoxypenols), and 9.04 to 26.4 wt % sugars. Other materialspresent include ketones, alcohol, and acids.

Suitable miscellaneous oxygenates include hydroxyacetaldehyde,hydroxypropanone, and acetol.

Examples of useful ketones are 3-ethyl-2-hydroxy-2-cyclopentenone,acetoxyacetone, 2-methyl-2-cyclopentenone, 3-methyl-2-cyclopentenone,1-hydroxy-2-butanone, 3-methyl-1,2-cyclopentanedione, 2-propanone, and2H-Pyran-2-one.

Useful furans include 2-acetylfuran, 5-methyl-2-furaldehyde,2-furaldehyde (furfural) (0-0.07 wt %), furantetrahydro-2,5-dimethoxycis, furantetrahydro-2,5-dimethoxy trans, furfuryl alcohol (2-furanmethanol) (0.15-0.16 wt %), 3-methyl-2(5H)-furanone (0.07-0.62 wt %),and 3-furan methanol.

Suitable phenols are phenol, o-cresol, p-cresol, m-cresol,2-methyl-4-propylphenol, 3,4-dimethylphenol, 2,4-dimethylphenol,2-ethylphenol, 3-ethyl phenol, hydroquinone, and 2,5-dimethylphenol.

Exemplary guaiacols are guaiacol, 4-acetoneguaiacol, 4-ethylguaiacol,4-methylguaiacol, isoeugenol cis, isoeugenol trans, eugenol, andvanillin.

Syringols that are useful include syringol, syringaldehyde,acetosyringene, and 4-methylsyringol.

Amongst the alcohols typically present is methanol.

Suitable acids are formic acid, propianic acid, and acetic acid.

Exemplary sugars include levcglucosan.

Bio-oil is a dark-brown, mobile liquid derived from the thermo-chemicalprocessing of biomass. Bio-oils generally contain water andlignin-derived oligomers. Lignin is a highly-available, well-studiedbio-polymer known for its antioxidant properties. For asphalt pavements,oxidation can cause deterioration via long-term aging and eventuallyresult in cracking. The present invention relates to lignin-containingbio-oil formulations as a substitute for asphalt binders, andoptimization of the bio-oil formulation. Using bio-oil formulations as asubstitute in asphalt production represents an economical alternative toconventional methods while being conscious of the environment andincreasing the longevity and performance of asphalt pavements. As apavement ages, it becomes stiffener and more susceptible to failure. Inan embodiment of the present invention, polyethylenes were blended withdifferent bio-oils to formulate asphalt substitutes. The use of bio-oilformulations as an asphalt substitute is an attractive way to increasethe longevity and enhance the performance of pavements.

In an embodiment of the present invention, bio-oil formulated as anasphalt binder substitute can include asphalt additives. Suitable gradesof asphalt additives include the following: PG52-22, PG58-22, PG64-22,PG67-22, PG70-22, PG76-22, PG82-22, PG52-28, PG58-28, PG64-28, PG67-28,PG70-28, PG76-28, PG52-34, PG58-34, PG64-34, PG64-16, PG67-16, PG70-16,PG76-16, PG64-10, PG67-10, PG70-10, PG76-10, pen grade 40-50, pen grade60-70, pen grade 85-100, pen grade 120-150, AR4000, AR8000, AC10 grade,AC20 grade, and AC30 grade. F. Roberts et al., “Hot Mix AsphaltMaterials, Mixture Design, and Construction,” NAPA Research andEducation Foundation (2nd ed.) (1996), which is hereby incorporated byreference in its entirety.

The bio-oil is preferably produced from a fast pyrolysis process ofbiomass, which consists of polymers of cellulose, hemicelluloses, andlignin. Examples include, but are not limited to oak wood, switch grass,and corn stover. Preferably, the bio-oil is recovered as fractions withdistinct properties, including one or more fractions that are relativelylow in water content, preferably less than about 8% by weight of thebio-oil, and has a lignin oligomer/poly phenol content in the range ofabout 30% to about 80% by weight. More preferably, the bio-oil has awater content of less than about 4% by weight, and most preferably fromabout 3% to about 4% by weight. More preferably, the bio-oil has alignin oligomer/polyphenol content of from about 50% to about 60% byweight.

The bio-oil formulation includes a polymer additive, such aspolyethylenes, oxidized polyethylenes, polyolefins, PE homopolymers, andthe like. The polymer additive can include low molecular weightpolymers, such as low, medium, or high density polyethylenes having amaximum viscosity of 1000 cps at 140° C. Other suitable polymers wouldinclude ethylenes and polypropylenes with melting points below 140° C.The polymer additive is preferably added at a concentration of up toabout 8% by weight of the bio-oil. More preferably, the polymer additiveis added at a concentration of from about 6% to about 8% by weight ofthe bio-oil. The polymer additive is added to the bio-oil at atemperature ranging from about 100° C. to about 130° C. utilizingmechanical agitation/mixing.

The bio-oil formulation binder preferably serves as a 100% replacementfor the asphalt binder. The bio-oil formulation can be mixed withvarying amounts of asphalt, for example, in amounts ranging from about99% to about 1% bio-oil and from about 1% to about 99% asphalt. In apreferred embodiment, the bio-oil formulation binder includes from about99% to about 40% by weight bio-oil, from 1% to about 8% by weightpolymer additive, and optionally from about 0% to about 59% by weightasphalt additive.

In one embodiment, the bio-oil formulation binder can be mixed withwater and a surfactant and mechanically agitated, in for example, ashear mill, to form an emulsion. Suitable emulsion-forming surfactantsare known to those of skill in the art. The emulsified bio-oil bindercan be used as weather-proofing sealant or as an adhesive bonding layerbetween two surfaces.

In another embodiment of the present invention, a composite materialincludes a mineral aggregate and a bio-oil formulation which binds themineral aggregate at an air void content of from about 2% to about 28%according to procedures known to one of skill in the art. The bio-oilbinder can be mixed with mineral aggregate typically composed of sand,gravel, limestone, crushed stone, and mixtures thereof. The compositematerial includes pavement material.

One form of the composite material is roofing shingles. The bio-oilbinder containing the polymer additive is mixed with fiberglass andmineral aggregate typically composed of lime dust and/or granularceramic material, such as manufactured ceramic material to form roofingshingles. The shingles can also include manufactured sand, e.g., crushedand washed mined aggregate, and also a blend of ceramic material andmanufactured sand. The roofing shingles can also include modifiedasphalt containing a Fischer-Tropsch wax, polyethylene wax, and/oroxidized polyethylene wax.

In another embodiment, the present invention includes a method for theproduction of a bio-oil formulation wherein the polymer additive iscombined with a pretreated bio-oil, heated to a temperature of fromabout 100° C. to about 130° C., and mixed until substantiallyhomogeneous. Optionally, when forming an emulsion, water and asurfactant can be added to the homogeneous asphalt binder mixture.During pretreatment, the bio-oil can be blended in, for example, a shearmill for up to about 8 hours. Industrial processes such as use of an inline shear mill could produce analogous pretreatment of the bio-oil bymixing for less than a minute under the proper conditions. The mixturecan be blended at about 500 rpm or more, preferably about 3000 rpm. Apretreatment procedure includes removing most of the water and the morevolatile components through the combination of mechanical mixing at atemperature range of from about 100° C. to about 130° C. resulting in anincreased viscosity but preferably less than about 3 Pascal seconds at atemperature range of from about 100° C. to about 130° C. with an agingindex of preferably 12 or less when measured from about 2 hours to about8 hours. The aging index is defined as:

${{Aging}\mspace{14mu} {Index}} = \frac{{Viscosity}\mspace{14mu} {of}\mspace{14mu} {Aged}\mspace{14mu} {Binder}}{{Viscosity}\mspace{14mu} {of}\mspace{14mu} {original}\mspace{14mu} {Binder}}$

In another embodiment of the present invention, the polymer additive iscombined with pretreated bio-oil, heated to a temperature of from about100° C. to about 130° C., and mixed in a shear mill to form asubstantially homogeneous mixture.

The mixture has a viscosity of from about 100 to about 1000 cps whenplaced in a rotational viscometer and tested at about 20 rpm at atemperature of from about 100° C. to about 130° C. The homogenousmaterial can be graded according to AASHTO MP3 and used as a substitutefor asphalt binder in paving projects.

EXAMPLES

The present process includes converting the biomass (corn stovers,switchgrass, woods, or other carbohydrate material containingcellulosic, hemi-cellulosic, or lignin material) into liquid form fromwhich so-called pyrolytic lignin can be separated by extraction usingwater. Fast pyrolysis of biomass produces bio-oil, gas, and char. Thegas stream containing H₂, CO, CO₂, and hydrocarbons can be used toprovide the heat required for the pyrolysis. Char that is produced canbe burned to provide heat for the pyrolysis, returned to the soil toenhance soil fertility, or recovered for sale (as activated carbon). Inone embodiment, developed at Iowa State University, the bio-oil producedwas collected into five separate fractions using a combination ofcondensers and electrostatic precipitators as described in R. Williamset al., “Utilization of Fractionated Bio Oil in Asphalt,” TransportationResearch Board 88th Annual Meeting, p. 19 (2009), which is herebyincorporated by reference in its entirety. The separation of bio-oilinto multiple fractions by using a fractionation system enablesselection of bio-oil fractions that are optimal for use as an asphaltsubstitute, or to be extracted for their lignin portions. Of particularinterest are the fractions originating from high molecular weightcompounds. These leave the pyrolyzer as aerosols, which are captured bythe ESPs (i.e. electrostatic precipitators).

Experiments producing bio-oil from the selected biomass materials wereconducted by using a 25 kWt fast pyrolysis system developed at IowaState University by the Center for Sustainable Environmental Technology(CSET). The pilot unit was composed of a 16.2 cm diameter fluidized bedreactor, a burner to externally heat the reactor, a two-stage auger tofeed the solid, two cyclones to remove particulate matter, and a bio-oilcollection system. The system can process 6-10 kg/h of solid feed. Themulti-stage bio-oil collection system recovers bio-oil as distinctfractions referred to as “stage fractions.” In this particularmanifestation of the bio-oil recovery system, five stages were employedwith the first four stages consisting of condensers and the last stageconsisting of an electrostatic precipitator designed to collect aerosolssuspended in the gas stream exiting the pyrolyzer. Other configurationsof condensers and electrostatic precipitators have been subsequentlybuilt and tested but share in common with this original configurationthe use of electrostatic precipitators to collect aerosols. The stagefraction from the recovery of these aerosols have proved particularlyattractive in the production of bio-oil binder formulations.

In these examples, stage fractions of bio-oil recovered from the ESPstage of the bio-oil collection system was used. The so-called ESPfractions from the pyrolysis of corn stover, oak wood, and switch grasswere each combined with polymer additives to optimize the bio-oilbinders.

Example 1

The following example relates to the pretreatment procedure for varyingthe pretreatment temperature and duration of the pretreatment and itsimpact on the aging index as shown in FIGS. 1 through 4.

The following protocol/procedure was used to develop bio-binders frombio-oils and to investigate the applicability of using these developedbio-binders as pavement materials. The testing protocol/procedure can besummarized as follows.

-   -   Step 1: The viscosity of the virgin/untreated bio-oil is        measured versus time at different temperatures. The suggested        times are at 0, 0.5, 1, 2, 4 and 8 hours and the suggested        temperatures are 100° C., 110° C., 120° C., and 130° C. The        viscosity versus time at different temperatures is plotted and        named as plot 1. The y-axis and the x-axis represent the        viscosity and time, respectively. FIGS. 1 through 4, FIGS. 11        through 22, and FIGS. 29 through 34 are examples.    -   Step 2: the aging index at varying durations is measured using        the following equation. The threshold value for the aging index        for bitumen binders is preferably 12.

${{Aging}\mspace{14mu} {Index}} = \frac{{Viscosity}\mspace{14mu} {of}\mspace{14mu} {Aged}\mspace{14mu} {Binder}}{{Viscosity}\mspace{14mu} {of}\mspace{14mu} {original}\mspace{14mu} {Binder}}$

-   -   Step 3: the pre-treatment/upgrading procedure is determined        based on steps 1 and 2. From plot 1, the pre-treatment duration        is the point at which the slope of the viscosity-time        relationship is changing. The pre-treatment temperature is        determined based on the measured viscosity from between about 2        to about 8 hours. It is preferred to have viscosity of less than        about 3 Pa·s and an aging index of less than the threshold value        (i.e. 12) when measured after about 2 hours to about 8 hours. It        is recommended to have a pre-treatment temperature higher than        100° C. to be sure that most of the volatile materials and water        content be evaporated.    -   Step 4: the viscosity at different temperatures and shear rates        is measured to determine the relationship between viscosity, and        temperature and shear rate. The recommended temperature range is        between 70° C. and 160° C. while the recommended shear rate        range is between 20 and 100 rpm. The relationships between        viscosity (y-axis) and temperature (x-axis) at the same shear        rate (preferred to be 20 rpm) is plotted and named as plot 2.        Examples are shown in FIGS. 5 through 10. The relationship        between viscosity and temperature at Viscosity of Aged Binder        for the same shear rate of the commonly used bitumen binders is        included in this plot. The relationships between viscosity        (y-axis) and shear rate at different temperatures (x-axis) is        plotted and named as plot 3. Examples are shown in FIGS. 23        through 28.    -   Step 5: the pre-treated/upgraded bio-oil is blended with        different types of polymer modifiers with different percentages.        The relationship between viscosity and temperature for the        modified bio-binders is measured and added to plot 2 and renamed        as plot 3. Examples are shown in FIGS. 23 through 28. Based on        plot 3, the bio-binder that resembles commonly used bitumen        binders is preferred to be used. Otherwise, the bio-binder to be        used as a pavement material is chosen based on pavement design        criteria.    -   Step 6: the mixing and compaction temperatures for the        bio-binder is determined based on plot 2 for step 4.    -   Step 7: the bio-binder undergoes RTFO and PAV aging in order to        simulate in-situ aging during the mixing and compaction process        (short term), and in-service period (long term). The RTFO        procedure is modified to comply with the bio-binders properties.        The recommended temperature for the RTFO is 110° C. to 120° C.        The RTFO duration ranges between 10 minutes and 40 minutes and        the recommended duration, based on this research, is 20 minutes.        Using the DSR, the G*/sin(delta) values for 25-mm sample plates        for the RTFO-aged bio-binders is determined at varying        durations. Then, the RTFO indexes based on the following        equation is calculated and compared to RTFO index of bitumen        binders (2.2) in order to determine the appropriate RTFO        duration. The PAV temperature may not be modified because it is        in the range of 90° C. and 110° C.; however, the temperature of        the degassing equipment is modified to comply with the        properties of the bio-binders. The preferred degassing        temperature based on this procedure is 120° C.

${R\; T\; F\; O\mspace{14mu} {Index}} = \frac{\left( {G*{/\sin}\; {delta}} \right)_{aged}}{\left( {G*{/\sin}\; {delta}} \right)_{unaged}}$

-   -   Step 8: the amount of evaporation occurring due to RTFO aging is        calculated based on the following equation. This step is        considered in the process of designing the pavement mixture.

${{Mass}\mspace{14mu} {change}} = {\frac{{{Aged}\mspace{14mu} {mass}} - {{Original}\mspace{14mu} {mass}}}{{Original}\mspace{14mu} {mass}} \times 100}$

-   -   Step 9: the performance grade is determined including the high,        intermediate, and low temperature performance grade. The high        temperature performance grade is determined based on the unaged        and the RTFO-aged bio-binders using 25-mm samples in the DSR.        The intermediate temperature performance grade is determined        based on 8-mm samples on the DSR after the bio-binders undergo        RTFO and PAV aging. The low temperature performance grade is        determined after the bio-binders undergo RTFO and PAV aging        using the BBR without changing or modifying the Superpave        procedure.    -   Step 10: using Richard's curve, the master curve for the        developed bio-binders is plotted and named as plot 4. The master        curve for the bitumen binder is included in plot 4. FIG. 35 is        an example. This plot shows the comparison between the overall        behavior of the developed bio-binder and bitumen binders at        different temperatures and frequencies. The following guidelines        are preferably followed to construct the master curves for the        bio-binders:        -   Rotational viscometer: conduct tests at four or five high            temperatures (pre-treated/upgraded and unaged residues).        -   DSR: conduct tests using a 8 mm plate for two or three            intermediate temperatures with different frequency sweeps            (pre-treated/upgraded, and RTFO and PAV aged residues).        -   BBR: conduct tests at two or three low temperatures            (pre-treated/upgraded, and RTFO and PAV aged residues).

Example 2

In this example, bio-oils were extracted from different biomassmaterials using an existing 25 k Wt fast pyrolysis system developed atIowa State University by CSET. The different biomass feedstocks wereoakwood, switchgrass, and cornstover. The pilot unit consists of a 16.2cm diameter fluidized bed reactor, a burner to externally heat thereactor, a two-stage auger to feed the solid, two cyclones to removeparticulate matter, and a vapor-condensing system consisting of fourcondensers and an electrostatic precipitator. The system can process6-10 kg/h of solid feed.

The separation of bio-oils into multiple fractions was conducted using afractionation condenser system which facilitated the selection ofbio-oil fractions that would be optimal for being used as a pavementbinder. As an example, Table 1 shows the properties of bio-oil fractionscollected from fast pyrolysis of cornstover. It can be seen that thosebio-oil fractions have significantly different properties, especially inwater and pyrolytic lignin contents. Bio-oil fractions collected fromcondensers #1 and #2 and ESP have high pyrolytic lignin content and lowwater content, which make them most suitable for using as pavementbinders.

TABLE 1 Properties of Bio-oils Fractions Collected from Fast Pyrolysisof Cornstover Property Cond. 1 Cond. 2 Cond. 3 Cond, 4 ESP Fraction oftotal oil 6 22 37 15 20 (wt %) pH — 3.5 2.7 2.5 3.3 Viscosity @ 40° C.(cSt) Solid 149 2.2 2.6 543 Lignin Content (wt %) High 32 5.0 2.6 50Water Content (wt %) Low 9.3 46 46 3.3 C/H/O Molar Ratio 1/1.2/0.51/1.6/0.6 1/2.5/2 1/2.5/1.5 1/1.5/0.5

The viscosity of bio-oils increases due to the aging effect. Temperatureis the most driving variable that leads to the aging effect, and hencethe viscosity of the bio-oils. In addition, some phase separation mayalso happen. As a result, instability problems may arise that arebelieved to result from a breakdown in the stabilized microemulsion andto chemical reactions, which continue to proceed in the bio oils.

The amount of aging that occurred in binder during production and inservice can be quantified in terms of viscosity as the Aging Index “AI”as shown in Equation 2.5. This aging index has been employed to evaluaterelative aging of asphalt cements of different grades and/or fromdifferent sources.

$\begin{matrix}{{{Aging}\mspace{14mu} {Index}} = \frac{{Viscosity}\mspace{14mu} {of}\mspace{14mu} {Aged}\mspace{14mu} {Binder}}{{Viscosity}\mspace{14mu} {of}\mspace{14mu} {original}\mspace{14mu} {Binder}}} & {{Equation}\mspace{14mu} 2.5}\end{matrix}$

Example 3

In this example, three types of polyethylene (homopolymers) were usedand their properties are summarized in Table 2. By definition,polyethylene “PE” is a polymer consisting of long chains of hydrocarbonmolecules of the monomer ethylene and it is a grade from polyolefins. Inaddition, polyethylene is a thermoplastic commodity heavily used inconsumer products. The ethylene molecule consists of C₂H₄, which arelinked together by a double bond.

The three polymer modifiers used can be classified as thermoplasticsaccording to the classification method aforementioned. These polymerswere provided by Honeywell International, Inc.

TABLE 2 Properties of Polymer Modifiers Used Oxidized PropertyPolyethylene 617 Polyethylene 680 Polyethylene 9 Drop Point, Mettler 101108 115 (° C.) Density (g/cc) 0.91 0.93 0.93 Viscosity @ 140° C. 180 250450 (cps) Bulk Density 563 536 508 (kg/m³)

The experimental matrix was designed to test all types of bio-oils withall three polymers modifiers at varying percentages. Each bio-oil wasblended with each polymer modifier at two and four percent by weight.Table 3 shows the different bio-oils and polymer modifiers at differentpercentages.

TABLE 3 Experimental Matrix of Bio-oils with Polymer Modifiers Bio-oilsPolymer Modifiers Oakwood Switchgrass Cornstover Polyethylene 617 0, 2,4 0, 2, 4 0, 2, 4 Oxidized Polyethylene 680 0, 2, 4 0, 2, 4 0, 2, 4Polyethylene 9 0, 2, 4 0, 2, 4 0, 2, 4

The amount of aging and oxidation was determined by measuring the agingindex according to Equation 2.5. The aging index was calculated for thevirgin bio-oils and the original bio-binders (after heat pre-treatment)by measuring the viscosity using the rotational viscometer for aged andunaged samples. For the virgin bio-oils, the aging index was determinedby measuring the viscosity of the aged bio-oils at 2, 4, and 8 hours andcomparing them to the viscosity of the unaged bio-oil (at 0 hours).Similarly, for the original bio-binders, the aging index was calculatedby measuring the viscosity of the aged developed bio-binders at 1, 2,and 4 hours and comparing them to the viscosity of the unaged originalbio-binder (at 0 hours).

The bio-oils tested had a high content of water and volatile materials.The pre-treatment/upgrading temperature was between 100° C. and 130° C.,which is the temperature required for the evaporation of water.Importantly, the pre-treatment temperature should be below thedecomposition temperature of the chemical constituents of bio-oils(cellulose, hemicellulose, and lignin). It was noted that the rates ofchange of viscosity over 8 hours were variable and the aging andhardening of bio-oils after two hours were high, so the pre-treatmentduration should be less than two hours because developing a bio-binder,initially, having a high viscosity may lead to mixing and pavementperformance problems. Notably, the viscosity of the bio-oils aftertwo-hours of heating were below the viscosity specified by the Superpaveat 140° C., which is 3 Pa·s. Therefore, the pre-treatment/upgradingduration is preferably a two-hour period.

Introduction to Superpave Specifications and Procedures

Superpave (Superior Performing Asphalt Pavements) is a product of SHRPasphalt research. The SHRP was established by Congress in 1987 toimprove the performance and durability of United States roads and tomake roads safer for both motorists and highway workers. SHRP researchfunds were used for the development of performance based asphaltspecifications to directly relate laboratory analysis with fieldperformance. The Superpave system incorporates performance based asphaltmaterials characterization with the design environmental conditions toimprove performance by limiting the potential for the asphalt binder tocontribute toward permanent deformation, low temperature cracking, andfatigue cracking in asphalt pavements.

One important distinction between typical asphalt specifications and theSuperpave specifications is the overall format of the requirements. Therequired physical properties remain constant for all of the performancegrades (PG). However, the temperatures at which these properties must bereached vary depending on the climate in which the binder is expected tobe used. The Superpave tests measure physical properties that can berelated directly to field performance by engineering principles. TheSuperpave binder tests are also conducted at temperatures that areencountered by in-service pavements. Table 4 lists the binder testequipment and a brief description of how each test is used in theSuperpave specifications. Table 5 describes how each test provides someindication of binder performance; however, the pavement structure andmixture proportions will have additional bearing on this performance.

TABLE 4 Superpave Binder Test Equipment Equipment Purpose Rolling ThinFilm Oven (RTFO) Simulate binder aging (hardening) Pressure Aging Vessel(PAV) characteristics due to production and construction processes(RTFO) and in-situ conditions (PAV) Dynamic Shear Rheometer (DSR)Measure binder stiffness and elasticity properties at high andintermediate temperatures (G* and δ) Rotational Viscometer (RV) Measurebinder viscosity at high temperatures for selection of mixing andcompaction temperatures Bending Beam Rheometer (BBR) Measure lowtemperatures stiffness Direct Tension Tester (DTT) and failureproperties

TABLE 5 Superpave Laboratory Tests and Relation to Performance TestEquipment Performance Property Rotational Handling Flow Viscometer→Pumping→ Dynamic Shear Permanent Rutting Rheometer→ Deformation→ FatigueStructural Cracking→ Cracking Bending Beam Thermal Low Rheometer→Cracking→ Temperature Direct Tension Tester→ Cracking

The main theme of the Superpave binder specifications is its relianceand dependence on testing asphalt binders in conditions that mimic thethree critical stages during the binder's life. First, tests conductedon the original binder represent the first stage of transport, storage,and handling of the binder. Second, tests performed on the RTFO residuebinder represent the second stage that the binder undergoes during mixproduction and construction. The second stage of tests is simulated forthe specification by aging the binder in a rolling thin film oven(RTFO). Third, tests conducted on the pressure aging vessel (PAV)residue binder displays the third stage that the binder ages over a longperiod of time in-situ as part of the hot mix asphalt pavement layer;this stage is simulated by aging the RTFO residue binder in the PAV.

Testing Procedures and Concepts

The different testing procedures used in these examples include:rotational viscometer (RV″), blending and mixing of polymer modifiers,rolling thin film oven (RTFO), pressure aging vessel (PAy), dynamicshear rheometer (DSR), and bending beam rheometer (BBR).

Rotational Viscometer (RV)

This test was used to determine the flow characteristics of the virginbio-oils (untreated) and the developed bio-binders (heat pre-treatedbio-oils). The data acquired by rotational viscometer were used todetermine the temperature and duration required for pre-treatment, toevaluate and quantify the amount of oxidation and aging that occurs, tomeasure the mixing and compaction temperatures at the hot mixingfacility, and to determine the viscoelastic behavior of the developedbio-binders. The rotational viscometer was conducted by measuring thetorque required to maintain a constant rotational speed of a cylindricalspindle at a specific temperature or measuring the torque at differentrotational speeds at different temperatures. The torque applied isdirectly related to the binder viscosity.

The rotational viscometer procedure was varied based on the requireddata or measurement that was needed. In order to determine thepre-treatment temperature and duration and to evaluate and quantify theamount of oxidation and aging occurred, the following test was conductedin accordance to ASTM D 4402 (2006) and summarized as follows:

-   -   30 grams of bio-oil were heated in an oven until sufficiently        fluid to pour.    -   The sample was stirred during heating to remove entrapped air.    -   8 or 11 grams were used typically according to the size of        spindle.    -   The temperature was kept constant.    -   The motor was set to operate at 100 rpm.    -   The viscosity reading and the percent torque should be between 2        and 98%. If the percent torque was out of the range, the size of        the spindle should be changed.    -   The five readings required for the report were: viscosity, test        temperature, spindle number, speed and percent torque.    -   Three viscosity readings were recorded at 1-minute intervals and        the reported value was the average of them.    -   The viscosity readings were recorded at 0, 30, 60, 120, 240, and        480 minutes at two different temperatures of 125° and 135° C.

In order to determine the mixing and compaction temperature of thedeveloped bio-binders, the same aforementioned procedures were followedexcept that the viscosity readings of the developed bio-binder(pre-treated bio-oils) were recorded just after 15 minutes (from turningon the rotational viscometer) and at four different temperatures rangingfrom 70° C. to 145° C.

In order to determine the viscoelastic behavior of the bio-oils or thedeveloped bio-binders, the following test was conducted in accordance toASTM D 4402 (2006) and summarized as follows:

-   -   The motor was set to operate at different speeds; 5, 10, 20, 40,        80, and 100 rpm.    -   The temperature was kept constant during measuring viscosity of        the developed bio-binder at different motor speeds.    -   The viscosity readings were recorded at 0, 30, 60, and 120        minutes.    -   The entire procedure was repeated for other temperatures ranging        between 70° C. and 160° C. to study the effect of temperature on        the viscoelastic properties of the developed bio-binders.

Rolling Thin Film Oven (RTFO)

The RTFO procedure served two purposes. The first was to provide an agedbinder that can be used for further testing of physical properties. Thesecond was to determine the mass quantity of volatiles lost from thedeveloped bio-binder during the process. Volatile mass loss was anindication of the aging that may occur in the binder during mixing andconstruction operations. Therefore, the main objective of RTFO was tomeasure the effect of temperature and moving current of air on theproperties of the semi-solid developed bio-binders.

The test was conducted in accordance to ASTM D 2872 (2004) andsummarized as follows:

-   -   According to Superpave specifications and procedures, the aging        temperature, originally, should be 163° C. and the aging        duration should be 85 minutes. As the chemical structure of the        original bio-binder may change due to this high temperature,        these temperature and duration were modified. The temperature        was adjusted and kept constant at 110° C. but the duration was        changed accordingly. The G*/sin(delta) of the original binder        calculated by the DSR should be at least 1.00 kPa and the        G*/sin(delta) of the RTFO residue of the developed bio-binder        calculated by the DSR should be at least 2.2 kPa. This means        that the G*/sin(delta) had increased by about 120%. Therefore,        the temperature of the RTFO was adjusted and kept constant at        110° C. and the durations were changed ranging between 60, 80,        100 and 120 minutes and the G*/sin(delta) were determined until        the G*/sin(delta) values were increased by 120%. The duration at        which the DSR value increased by 120% was considered the RTFO        duration.    -   The RTFO oven was preheated to the aging temperature, 110° C.,        for a minimum of 16 hours prior to use.    -   The binder sample was heated until fluid, not exceeding 120° C.    -   Eight sample bottles were required for Superpave binder testing.        Two samples (bottles) were required for the mass loss        determination. The other six were used for further testing.    -   RTFO bottles were loaded with 50-60 grams of developed        bio-binders.    -   The bottles were turned on their side to a horizontal position        and placed in a cooling rack for 10, 20, and 30 minutes. Then,        sample bottles were placed in the carriage and rotated at a rate        of 15 revolutions per minute.    -   The air flow was set at a rate of 4000 ml/min for the calculated        duration aforementioned. Then the weights of the bottles were        measured to the nearest 0.001 gram.    -   Calculation of mass loss was determined according to the        following equation:

${{Mass}\mspace{14mu} {change}} = {\frac{{{Aged}\mspace{14mu} {mass}} - {{Original}\mspace{14mu} {mass}}}{{Original}\mspace{14mu} {mass}} \times 100}$

Pressure Aging Vessel (PAV)

The PAV exposed the developed bio-binder to high pressure andtemperature for 20 hours to simulate the effects of long-term in-situaging. According to H. Bahia et al., “Strategic Highway Research ProgramBinder Rheological Parameters: Background and Comparison withConventional Properties,” Transportation Research Record, 1488:32-39(1995), which is hereby incorporated by reference in its entirety, thePAV procedure simulates 5-10 years of in-service aging. Generally, thePAV aged bio-binders were used to test the intermediate criticaltemperature with the DSR. Since pavement binders exposed to long-termaging have also been through the mixing and construction process, thePAV procedure requires that the samples used should have been aged inthe RTFO. In other words, PAV procedure was performed on RTFO residuedeveloped bio-binder samples.

The test was conducted in accordance to ASTM D 6521 (2004) andsummarized as follows:

-   -   The PAV procedure used developed bio-binder aged in the RTFO.        The pressure vessel was designed to operate under the pressure        and temperature conditions of the test (2070 kPa and either 90°,        100°, or 110° C.). The vessel must accommodate at least 10        sample pans. The oven should be able to control the internal        temperature of the PAV to within ±0.5° C. during the aging        period. In this procedure, the temperature was set to 100° C.    -   The RTFO-aged bio-binder was heated until fluid and stirred to        ensure homogeneity.    -   Three PAV sample pans of 50 grams each were prepared and placed        in the sample rack.    -   The sample rack with the samples was placed in the hot vessel        and the lid was quickly secured to avoid excessive heat loss.    -   The aging process was conducted at different temperatures        depending on the design climate.    -   When the vessel temperature was within 2° C. of the required        temperature, the pressure was applied and the timing for the        aging periods begun.    -   After 2.5 hours, the pressure was gradually released—8 to 10        minutes were usually required (if the pressure was released too        quickly, foaming may occur).    -   The sample rack was then removed from the rack and placed in the        oven at 100° C. (instead of 163° C. for bitumen binders) for 15        minutes. The temperature was set to 100° C. instead of 163° C.        as the chemical structure of the bio-oils may change        considerably at this high temperature.    -   The sample was then transferred to a storage container and        degassed in a 120° C. (instead of 170° C. for bitumen binder)        vacuum oven for 30 minutes at a pressure of 15 kPa absolute. The        temperature was set to 120° C. instead of 170° C. due to the        aforementioned reason.    -   PAV report included many readings that can be listed as follows:        sample identification, aging test temperature to the nearest        0.5° C., maximum and minimum aging temperature recorded to the        nearest 0.1° C., total time during aging that temperature was        outside the specified range to the nearest 0.1 minute and total        aging time in hours and minutes.

Dynamic Shear Rheometer (DSR)

Since pavement binder behavior depends on both temperature and loadingtime, the ideal test for binders should include both factors. Rheometersare adaptable for use in testing, so both time and temperature effectscan be evaluated. The main objective of dynamic shear rheometer testingwas to measure the rheological properties (shear modulus and phaseangle) at intermediate to high temperatures using parallel plategeometry and was typically applicable to unaged and RTFO aged samples.

The test was conducted in accordance to ASTM D 7175 (2005) andsummarized as follows:

-   -   The developed bio-binder binder was heated until fluid with        stirring to remove air bubbles and achieve a homogeneous sample.    -   The bio-binder was poured into silicon mold with the appropriate        diameter and thickness for testing (because lighter constituents        of the binder may be absorbed by the silicone, care should be        taken not to let the sample sit in the mold for any more than        two hours before loading it in the DSR).    -   The bio-binder specimen should be attached to the plates of the        DSR. Then, the DSR plate was lowered down automatically.    -   The specimen was trimmed flush with the parallel plates, and the        extra 50 microns was “dialed out” so that the gap is exactly at        the desired value.    -   The water was circulated through a temperature controller that        precisely adjusted and maintained the desired sample        temperature.    -   A computer controlled the DSR test parameters and recorded test        results (testing consisted of setting the DSR to apply a        constant oscillating stress and recording the resulting strain        and time lag, δ). The Superpave test procedures required that        the oscillation speed to be 10 radians/second. The rheometer        software automatically computed and reported G* and δ, using the        relationship between the applied stress and the resulting shear        strain.    -   The operator set the approximate value of shear strain “strain        amplitude”. Original (unaged) binder and RTFO aged binders were        tested at strain values of approximately ten to twelve percent.        PAV-aged bio-binders were tested at strain values of about one        percent. In all cases, strain values must be small enough that        the response of the binder (G*) remains in the linear        viscoelastic range.

Bending Beam Rheometer (BBR)

The bending beam rheometer (BBR) was used to determine the lowtemperature performance grade of a pavement binder. A BBR tested thedeveloped bio-binder at low service temperatures to determine itssusceptibility to thermal cracking as pavement binder is verysusceptible to thermal cracking at low temperatures due to the fact thatbio-binders becomes less viscous as they are cooled and contracts. Inother words, the BBR was used to measure how much a bio-binder deflectedunder a constant load at a constant temperature. The BBR tested pavementbinders that had been aged in both a rolling thin film oven and thepressure aging vessel. Therefore, the test measured the performancecharacteristics of bio-binders as they had been exposed to hot mixing ina mixing facility and some in-service aging.

The test was conducted in accordance to ASTM D 6648 (200 1) andsummarized as follows:

-   -   Test specimens were prepared using a rectangular aluminum mold.        The inside surfaces of the two side plates and base plate were        lightly greased with petroleum-based jelly. The mold was then        assembled and held together with two rubber O-rings.    -   The developed bio-binder was heated until fluid (usually about        110° C., but not to exceed 120° C.) and poured into small,        rectangular aluminum beams.    -   After a cooling period of about 45 to 60 minutes, excess binder        was trimmed from the upper surface using a hot spatula. Then,        the specimen remained in the mold at room temperature, but no        longer than two hours.    -   The specimen was stored below −0.5° C. to allow for proper        handling. The beams were placed in a fluid bath that maintained        low temperatures.    -   After being in the fluid bath for one hour, the beams were        individually placed on a loading frame and subjected to a load        for 240 seconds.    -   The deflection was measured versus time, which was used to        calculate the two key properties of stiffness and change in        stiffness (m-value). A sample of bio-binder can fail at a given        temperature by either having a stiffness value “5” of greater        than 300 MPa or an m-value less than 0.300 (Asphalt Institute        2003).

Testing Sequence

The testing sequence of the rheological plan was conducted in subsequentstages. The first stage was concerned about measuring the viscosity ofthe virgin bio-oils with the rotational viscometer to determine thepre-treatment temperature and duration required. After the pre-treatmentprocedure, the second stage contained two tests, e.g. DSR and rotationalviscometer, on the original bio-binder (developed bio-binder). Then thethird stage was testing the RTFO bio-binder in the DSR after placing thebio-binder in the RTFO oven to simulate the short-term aging due tomixing and compaction processes. Finally, the RTFO bio-binder residuewas placed in the PAV oven to simulate the long-term aging due topavement performance, and then the PAV bio-binder was tested using DSRand BBR.

Determination of Rheological Properties Pretreatment Temperature andDuration

The pretreatment temperature and duration were determined after testingthe virgin bio-oils (with and without polymers modifiers) using therotational viscometer. The viscosity of the virgin bio-oils was measuredduring 8 hours at different temperatures, e.g. 125° C. and 135° C. Forinstance, the virgin bio-oil was kept at 125° C. in the rotationalviscometer for 8 hours and the viscosity values were measured at 0, 30,60, 120, 240 and 480 minutes. The viscosity of the virgin bio-oilsthroughout the whole period was compared to the viscosity specified inthe Superpave specifications and requirements, which is to be less thanabout 3 Pa·s. According to the relationship between viscosity and theduration, the pre-treatment temperature and duration were specified foreach virgin bio-oil and polymer modifier virgin bio-oil.

Mixing and Compaction Temperatures

The mixing and compaction temperatures were calculated in accordance tothe Superpave specifications and requirements. After the pretreatmentprocedure, the viscosity measurements of the original bio-binders atdifferent temperatures, e.g. 70, 80, 90, 100, 110, and 120° C., weremeasured using the rotational viscometer. Then, determining thetemperature range that corresponded to viscosity values of 0.17±0.02Pa·s was the range of mixing temperature. Likely, determining thetemperature range that corresponded to viscosity values of 0.28±0.03Pa·s was the range of compaction temperature.

In this example, the pre-treatment procedure for developing bio-bindersfrom bio-oils was determined for the three different bio-oils (oakwood,switchgrass, and cornstover). The pre-treatment procedure can also bereferred to as an upgrading procedure. The pre-treatment/upgradingprocedure was determined through measuring the viscosity of the bio-oilsat different temperatures (125 and 135° C.) over 8 hours, then the agingindexes were calculated based on equation 2.5. The viscositymeasurements were recorded using a Brookfield viscometer.

Viscosity Measurements and Aging Index before Treatment

The viscosity measurements for the tested bio-oils over the 8 hours at125° C. and 135° C. without pre-treatment were measured. FIG. 5 to FIG.7 and FIG. 8 to FIG. 10 display the viscosity over time for all thetested blends before treatment at 125° C. and 135° C., respectively.

Based on these figures, the following observations are noted. First, theviscosity of the unmodified oakwood, switchgrass, and cornstoverbio-oils (blends 1, 8 and 15, respectively) were very low due to thepresence of water and volatile materials. Besides, some viscositymeasurements at the first two hours were almost zero due to the presenceof water and volatile materials. Second, there was no considerabledifference between the viscosity measurements of the three unmodifiedbio-oils. Third, the rates of change of viscosity over time for most ofthe blends were not constant. In other words, the rate of change ofviscosity at the first two hours was different than the rate of changeof viscosity between 2 and 8 hours. During the first two hours, asignificant amount of evaporation and boiling took place due to thewater and volatile materials. This may be the reason that the rate ofchange of viscosity during the first two hours was less than the rate ofchange of viscosity between 2 and 8 hours. Fourth, the addition of thepolymer modifier led to a significant increase in the viscosity of theunmodified bio-oils.

The aging indices relative to zero and two hours were calculated andlisted in Table 6 and Table 7 at 125 and 135° C., respectively. FIG. 11to FIG. 13 and FIG. 14 to FIG. 16 display the aging indices at 125° C.for all the tested blends relative to zero and two hours, respectively.FIG. 17 to FIG. 19 and FIG. 20 to FIG. 22 represent the aging indices at135° C. for all the tested blends relative to zero and two hours,respectively. Based on these values, the following conclusions could bemade. First, the aging indices after four hours were below 12 (thethreshold value of bitumen binders) for all blends at 125° C. and 135°C. (except blend 8 at 135° C.). In addition, the aging indices after 8hours were ranging between 1.78 and 20.75 and 3.46 and 32.00 for 125° C.and 135° C., respectively. This indicated that increasing thetemperature led to higher aging indices and this was expected as thetemperature is a significant factor in increasing the oxidationoccurring in the bio-oils. However, when the aging indices weredetermined relative to two hours, they were below 12 for all blends.Therefore, it can be concluded that if the bio-oils werepre-treated/upgraded, the aging indices of the bio-oils would decreaseand become below the assumed limiting value (12) and would be comparableto bitumen binders. Second, the aging indices relative to zero after 8hours for the unmodified bio-oils were—in general—higher than 12 whichindicated that significant amount of oxidation took place in thebio-oils due to the high content of oxygen present in the bio-oils.Third, the addition of polymer modifiers did not lead to a decrease inthe aging indices of the bio-oils. In other words, no specific trendcould be noted in the aging indices after the addition of a polymermodifier. Overall, it may be concluded that a pre-treatment/upgradingprocedure was required for the bio-oils to stabilize them throughdecreasing the water and volatile materials content and consequentlydecrease the aging indices.

TABLE 6 Aging Index Relative to Zero and Two Hours before Treatment at125° C. Aging Index relative Aging Index relative Blend to zero to two #0.5 1 2 4 8 4 8 1 1.21 1.53 2.89 4.87 14.32 1.68 4.95 2 1.44 1.67 1.482.63 6.23 1.77 4.19 3 1.31 1.58 2.08 3.74 8.60 1.80 4.13 4 1.28 1.522.15 3.56 11.41 1.66 5.31 5 1.50 2.17 3.52 6.31 18.65 1.79 5.30 6 1.662.41 4.03 9.46 20.75 2.35 5.15 7 1.16 1.35 1.67 2.32 3.89 1.39 2.33 81.63 2.44 3.74 6.81 15.63 1.82 4.18 9 1.09 1.29 1.83 2.93 5.90 1.60 3.2310 1.23 1.47 2.10 3.71 7.94 1.76 3.77 11 1.13 1.32 1.70 3.02 6.04 1.783.56 12 1.08 1.24 1.61 2.16 3.31 1.35 2.06 13 1.08 1.24 1.67 2.55 5.421.53 3.24 14 1.07 1.26 1.82 2.87 5.13 1.58 2.82 15 1.25 1.58 1.93 2.704.25 1.40 2.21 16 1.25 1.58 2.10 3.07 5.98 1.46 2.84 17 1.20 1.54 2.003.05 5.38 1.53 2.69 18 1.15 1.38 1.62 2.26 3.20 1.40 1.98 19 1.19 1.311.63 2.10 3.10 1.29 1.91 20 1.00 1.17 1.42 2.08 3.12 1.47 2.20 21 1.041.08 1.12 1.16 1.78 1.04 1.59

TABLE 7 Aging Index Relative to Zero and Two Hours before Treatment at125° C. Aging Index relative Aging Index relative Blend to zero to two #0.5 1 2 4 8 4 8 1 1.76 3.08 4.89 10.84 30.84 2.22 6.30 2 1.34 1.51 1.873.58 8.80 1.91 4.70 3 1.57 2.17 3.80 7.11 16.80 1.87 4.42 4 1.67 2.253.75 9.05 26.25 2.41 6.99 5 1.44 1.90 2.97 5.69 11.95 1.91 4.02 6 2.132.54 3.58 5.56 9.54 1.55 2.67 7 1.09 1.18 1.33 1.61 2.39 1.22 1.80 84.33 5.67 8.33 15.78 32.00 1.89 3.84 9 1.39 1.84 2.88 5.82 12.63 2.024.38 10 0.83 1.01 1.59 3.50 11.54 2.20 7.28 11 1.32 1.76 2.64 5.06 16.271.92 6.18 12 1.09 1.45 2.04 4.02 9.83 1.97 4.81 13 1.10 1.26 1.82 3.8510.00 2.12 5.50 14 0.90 1.14 1.56 3.22 9.05 2.06 5.78 15 1.27 1.61 2.123.18 5.39 1.50 2.54 16 1.16 1.37 2.03 4.12 8.37 2.03 4.13 17 1.12 1.311.91 3.48 10.58 1.83 5.55 18 1.09 1.28 1.60 2.26 3.58 1.41 2.24 19 1.251.50 1.83 2.47 4.00 1.35 2.18 20 1.50 2.00 2.43 4.27 7.33 1.75 3.01 211.20 1.40 1.66 2.26 3.46 1.36 2.08Viscosity Measurements and Aging Index after Treatment

The viscosity measurements for the tested bio-oils over the 8 hours at125° C. and 135° C. with pre-treatment were measured. FIG. 23 to FIG. 25and FIG. 26 to FIG. 28 display the viscosity over time for all thetested blends after treatment at 125° C. and 135° C., respectively.Based on these figures, the following observations could be noted.First, the viscosity of the unmodified oakwood, switchgrass, andcornstover bio-oils (blends 1, 8 and 15, respectively) increased at 125°C. and 135° C. after treatment. This was expected as the treatment ledto a decrease in the water and volatile materials contents. Second, nospecific trend could be observed for the effect of treatment on theviscosity of the modified bio-oils at 125° C. and 135° C. Precisely, thetreatment procedure did not lead—in general—to an increase in theviscosity of the modified bio-oils. This may be due to the effect of theblending procedure of the polymer modifiers (polymer additives) with thebio-oils which incorporated heating for 30 minutes at 110-120° C.; thisblending procedure led to considerable variability in the viscosity ofthe modified bio-oils after treatment. Third, after treatment, the ratesof change in viscosity over time for most of the blends were constant.In other words, the rate of change in viscosity at the first two hourswas the same rate of change of viscosity between 2 and 8 hours. Fourth,during the first two hours, the amount of evaporation and boiling tookplace due to the water and volatile materials decreased due to thetreatment procedure. Fifth, the addition of the polymer modifier did notled to a specific trend in the sense of increasing the viscosity of theunmodified bio-oils. In summary, it may be concluded that the treatmentprocedure was effective in increasing the viscosity of the unmodifiedbio-oils due to the evaporation of water and volatile materials and thisat least in part lead to decrease the temperature susceptibility of thebio-binders developed from bio-oils.

The aging indices relative to zero hours were calculated and listed inTable 8 and Table 9 at 125° C. and 135° C., respectively. FIG. 29 toFIG. 31 and FIG. 32 to FIG. 34 represent the aging indices for all thetested blends relative to zero hours at 125° C. and 135° C.,respectively. Based on these values, the following conclusions can bemade. First, the aging indices relative to zero hours were decreased—ingeneral—after treatment compared to the corresponding values of agingindices before treatment. This may be due to the increase in viscosityof the bio-oils associated with the treatment procedure due to the lossof water and volatile materials. Second, there was variability in theaging indices after the treatment, precisely the aging indices for someblends increased after treatment. However, this variability was expecteddue to the variability associated with the blending procedure of thepolymer modifier, and with the bio-oils itself as a material.

TABLE 8 Aging Index Relative to Zero Hours after Treatment at 125° C.Aging Index relative to zero Blend # 0.5 1 2 4 8 1 1.14 1.29 1.74 2.896.29 2 1.04 1.14 1.29 1.64 2.29 3 1.12 1.25 1.50 2.00 3.06 4 1.06 1.321.74 2.97 5.26 5 1.17 1.65 2.52 3.98 9.68 6 1.07 1.25 1.71 2.95 4.91 71.15 1.30 1.57 2.21 3.36 8 1.18 1.41 1.97 3.47 8.73 9 1.03 1.19 1.581.94 3.06 10 1.18 2.06 4.12 6.34 11.59 11 1.00 1.17 1.50 2.38 5.17 121.06 1.26 1.44 2.32 3.15 13 1.12 1.18 1.49 2.03 3.27 14 1.00 1.03 1.181.28 1.70 15 1.06 1.32 1.90 3.01 5.23 16 0.98 1.22 1.51 2.42 4.76 171.02 1.12 1.36 1.85 2.67 18 1.34 1.64 2.23 4.12 8.24 19 1.19 1.39 1.843.58 5.86 20 1.10 1.23 1.50 2.35 3.50 21 1.43 1.67 1.71 1.86 2.48

TABLE 9 Aging Index Relative to Zero Hours after Treatment at 135° C.Aging Index relative to zero Blend # 0.5 1 2 4 8 1 1.15 1.27 1.73 3.088.65 2 1.05 1.15 1.39 1.79 2.73 3 1.00 1.00 1.13 1.46 2.05 4 1.22 1.391.66 2.26 3.66 5 1.14 1.34 1.91 4.53 18.25 6 1.12 1.26 1.55 2.16 5.25 71.21 1.69 2.66 3.41 5.55 8 1.37 1.71 2.47 3.66 15.85 9 1.18 1.41 1.852.98 5.06 10 1.14 1.37 1.75 4.07 10.85 11 1.36 1.73 2.41 3.55 6.69 121.30 1.57 2.00 3.09 5.00 13 1.16 1.32 2.08 2.76 5.12 14 1.25 1.63 1.812.63 4.56 15 1.44 1.78 2.51 4.11 8.02 16 1.22 1.49 2.21 3.71 9.71 171.37 1.65 2.05 3.12 5.19 18 1.42 2.09 3.17 5.66 15.08 19 1.26 1.68 2.445.33 12.03 20 1.19 1.34 1.63 2.28 3.80 21 1.16 1.38 1.69 2.48 3.94

Statistical Analysis

A statistical analysis was conducted, using the computer software JMP7.0, to study the statistical difference between the viscosity over timeand the aging indices of the bio-oils. A one-way analysis of variance“ANOVA” using the method of least squares was performed for evaluatingthe effect of heat treatment. Type I error (a) of 0.05 was used for allstatistical analysis as the confidence level was 95%. The p-values ofthe AVOVA for the viscosity over time and aging indices for bio-oilswere summarized and listed in Table 10 and Table 11, respectively. Asshown below, the statistical tests were grouped according to the bindertype and the temperature.

TABLE 10 Effect of Heat Treatment on the Viscosity over Time of Bio-oilsBinder Temp Type (° C.) V0 V0.5 V1 V2 V4 V8 Oakwood 125

0.0677 0.1042 0.2393 135

0.1638 0.2071 0.2781 0.4048 0.4038 Switchgrass 125

135

Cornstover 125 0.9779 0.9186 0.8641 0.8626 0.9436 0.9799 135 0.89350.7520 0.6226 0.6375 0.6964 0.7666 Bold, italic,*: statisticallysignificant Bold, italic: very close to statistically significant

TABLE 11 Effect of Heat Treatment on the Aging Index of Bio-oils BinderTemp. Type (° C.) AI0.5 AI1 AI2 AI4 AI8 Oakwood 125

0.0620

135

0.0720 Switchgrass 125 0.2233 0.5255 0.7271 0.4937 0.3917 135 0.51490.4518 0.3326 0.1447 0.0696 Cornstover 125 0.9398 0.9496 0.8526 0.35790.3875 135 0.3387 0.3429 0.2082 0.2846 0.2859 Bold, italic,*:statistically significant Bold, italic: very close to statisticallysignificant

Based on these results, the following conclusions can be established.First, the effect of the heat treatment on the viscosity over time andaging indices were dependent on the type of the bio-oil. In other words,the viscosity over time and aging index for the bio-oils were notaffected similarly due to heat treatment. From Table 10, the viscosityover time of the oakwood and switchgrass bio-oils was in generalaffected at 125° C. and 135° C., respectively. From Table 11, the agingindex of the oakwood was the only bio-oil affected by the heattreatment. Second, no specific trend could be noted for the effect ofthe treatment on the viscosity over time and aging indexes of thebio-oils. This may be due to the low temperature (100-110° C.) of thetreatment which led to evaporate the water content and the volatilematerials without affecting the physical and chemical properties of thebio-oils. In addition, no clear trend was observed for the effect ofheat treatment on viscosity due to the difference in temperature betweenthe heat treatment (100-110° C.) and the temperature at which theviscosity was being measured (125° C. and 135° C.). Overall, thestatistical analysis showed that the heat treatment procedure for thebio-oils had different effects on the viscosity over time and agingindex and the degree of this effect was dependent on the type of thebio-oil. Also, the heat treatment procedure may not lead to significantchanges in the physical and chemical properties of the bio-oils;however, the heat treatment procedure may be very important procedure toupgrade and stabilize the bio-oils through reducing the water andvolatile materials content.

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions, and the like canbe made without departing from the spirit of the invention and these aretherefore considered to be within the scope of the invention as definedin the claims which follow.

What is claimed:
 1. A method for the production of an asphalt bindersubstitute comprising: a) pretreating a bio-oil by mechanical mixing ata temperature of from about 100° C. to about 130° C. such that thebio-oil achieves a viscosity of less than about 3 Pa·s at a temperatureof from about 100° C. to about 130° C. and is equivalent to the bio-oilbeing mixed at a temperature of from about 100° C. to about 130° C. toachieve an aging index of less than about 12 after from about 2 to about8 hours; b) adding a polymer additive to the pretreated bio-oil; c)heating the blend at a temperature of from about 100° C. to about 130°C.; and d) treating the heated blend to a viscosity between about 100and about 1000 cps when measured in a rotational viscometer at about 20rpm and a temperature of from about 100° C. to about 130° C.
 2. Themethod of claim 1, wherein the bio-oil is produced from a fast pyrolysisprocess of a biomass.
 3. The method of claim 2, wherein the biomasssource of the bio-oil is a high lignin-content biomass.
 4. The method ofclaim 3, wherein the biomass is oak wood, switch grass, or corn stover.5. The method of claim 1, further comprising: e) adding an asphaltadditive to the pretreated bio-oil binder.
 6. The method of claim 5,wherein the bio-oil binder comprises the asphalt additive at aconcentration of up to about 59% by weight of the bio-oil binder.
 7. Themethod of claim 1, wherein the bio-oil binder comprises the polymeradditive at a concentration of from about 6% to about 8% by weight ofthe bio-oil binder.
 8. The method of claim 1, wherein the bio-oil bindercomprises up to about 8% by weight polymer additive.
 9. The method ofclaim 1, wherein the polymer additive comprises a polyethylene, oxidizedpolyethylene, polyolefin, PE homopolymer, or mixtures thereof.
 10. Themethod of claim 1, wherein the bio-oil binder includes from about 99% toabout 40% by weight bio-oil, from 1% to about 8% by weight polymeradditive, and optionally from about 0% to about 59% by weight asphaltadditive.
 11. The method of claim 1, further comprising: e) adding waterand a surfactant to the bio-oil blend to form an emulsion.
 12. Themethod of claim 11, wherein the bio-oil binder comprises a sealant or anadhesive.